Group B Streptococcus (GBS), also referred to as Streptococcus agalactiae, is found within the normal microflora of the gastrointestinal (GI) tract and genitourinary tract of a significant percentage of the adult human population. The bacterium can also colonize the upper respiratory tract. Although GBS are part of an individual's normal flora, the bacteria can cause septicaemia, meningitis and pneumonia amongst the elderly, immunocompromised individuals and, in particular, the neonatal population. GBS infection is the predominant cause of invasive bacterial disease in neonates.
GBS is a leading cause of early neonatal morbidity and mortality in the United States. GBS can be found in the vagina and/or rectum of 10-30% of pregnant women. Colonization status is usually determined by analysis of vaginal and rectal swabs. The CDC recommends screening for GBS at 35-37 weeks' gestation because GBS can be transmitted to neonates either before or during labor. If a woman tests positive for GBS colonization, she currently receives prophylactic antibiotic treatment. Antibiotic resistance testing may also be performed on positive samples from antenatal patients. While GBS-associated neonatal incidence has decreased substantially in recent years, GBS is still responsible for 2-3 cases of septicemia, meningitis and pneumonia per 1000 live births. Culture-based assays are currently the preferred method to detect GBS. However, obtaining results can take days, during which GBS colonization, which is transient, may occur. Therefore, a rapid and accurate screening test based on DNA to detect GBS is needed which would provide clinicians with an effective tool for identifying patients at risk of transmitting GBS to their newborns. This would in turn support effective monitoring and treatment regimens for the patients, as well as prevent overuse of antibiotics. Moreover, rapid and accurate detection of GBS infection would lead to more appropriate treatment.